"Police have confirmed this is being treated as a potential terrorist attack", May said.
The Metropolitan Police said that one man was pronounced dead at the scene and ten others were injured. Police have yet to provide any other update but reports have surfaced that 10 people are seriously injured.
The group's general secretary, Harun Khan, said that eyewitnesses saw the van driver hit a number of Muslims.
"Our priority is to assess the level and nature of injuries and ensure those in the most need are treated first and taken to hospital".
One man, who gave his name as Mohin, said his cousin was caught up in the incident. Labour leader Jeremy Corbyn, expressing shock over the incident, said in a statement, "I've been in touch with the mosques, the police and Islington council regarding the incident". London Mayor Sadiq Khan condemned the attack as an assault on "innocent Londoners, many of whom were finishing prayers during the holy month of Ramadan"-and on "all our shared values of tolerance, freedom, and respect", the Guardian reports".
Britain's terrorist alert has been set at "severe", meaning an attack is highly likely.
Flowers have been laid near Finsbury Park Mosque, while police officers have also arranged bouquets from members of the public inside the cordon.
Chairman of the Finsbury Park Mosque, Mohammed Kozbar has tweeted about the incident.
She said her thoughts were with the injured, their loved ones and emergency officials who responded to the incident. "Our prayers are with the victims".
"Given we are approaching the end of the month of Ramadan and the celebration of Eid with many Muslims going to local mosques, we expect the authorities to increase security outside mosques as a matter of urgency". A number of police and ambulances were in attendance.
London police closed the area to normal traffic.